This application relates generally to the field of maneuverable vehicle guidance. It relates to the guidance of space vehicles operating in an exoatmospheric environment and to guidance of air vehicles operating in an endoatmospheric environment. The application relates, in particular to the guidance of airframe ordinance which is released from a platform, typically a bomber or fighter aircraft. Such vehicles are commonly guided to the target with improved delivery accuracy using a variety of jet propulsion means powered by an onboard gas generator which is placed in operation at the time of launch and remains operational up to the point of impact. In the alternative, the propulsion means may be in the form of discrete solid propulsion thrusters.
As disclosed, for example, in the U.S. Pat. to Stein et al No. 5,076,511, where a gas generation system is used, there must be a feedback control to avoid excess manifold pressure or provision must be made for venting of at least one jet valve to continuously relieve at least some of the continuously generated gas. Neutral propulsion or zero propulsion is produced by opening two opposing valves simultaneously. The use of adjustable control surfaces is also possible, but because of necessary mechanical linkages, they are not practical for minor and continuous adjustments.
It is also known to provide a separately attachable modular booster to the tail of the vehicle as disclosed in the U.S. Pat. to Ripleyxe2x80x94Lotee et al No. 4,364,530.
In the above mentioned co-pending application Ser. No. 08/154,767, there is disclosed a relatively simple jet reaction control means of size sufficiently small to permit it to be installed in a forwardly positioned fuse well, wherein laterally oriented forces are imparted to the nose of the vehicle rather than through the center of gravity, so as to act as control forces to place the air vehicle at a desired angle of attack and side slip to magnify the control force by taking advantage of vehicle lift generated by cross flow drag at a given angle of attack and yaw. The system includes compact gas generating means feeding each of four bi-directional nozzles located on the periphery of a valve plate positioned 90 degrees one from the other on a valve plate element fed by the gas generating means. The valve plate element includes four pairs of solenoid operated poppet valves, one for each nozzle, which are cycled at rapid periodic intervals to vent the system of excess pressure and to change the force states being generated by the bi-directional nozzles to in turn control the air vehicle angle of attack and side slip.
The present invention relates to an improved method of using the above-described construction which produces far more sensitive control of the vehicle on its path of flight to the target. Because there are eight nozzles arranged in four oppositely directed pairs, each capable of independent operation, it is possible to generate an increased number of force states which are instantaneously available to meet any given thrust requirement, which may include adjustment of pitch and yaw, as well as speed of axial rotation. The system can produce force in the pitch and yaw plane by firing nozzles opposite from each other in the same direction which generates a control force which can be represented by a force of 2F through the centerline of the air vehicle and two canceling roll torques. When two adjacent nozzles are opened to produce a control force of 2F cos 45 degrees and two equal but opposite forces of F since 45 degrees, the resultant force again passes through the centerline of the missile. The force vector generated in the two cases both pass through the centerline of the missile to preclude inducing roll and the resultant forces are positioned at 45 degrees. When used for pitch and yaw correction, the resultant forces pass through the center line of the vehicle. As a result, the disclosed system provides three unique modes of operation, not available in prior art construction. It is possible to fire two adjacent nozzles to generate a force level of 2F cost 45 degrees; or four adjacent nozzles to generate a force level of 4 F cos 45 degrees; or two opposite nozzles to generate a force of 2 F, or combinations of these nozzles to generate 33 different force states. In addition, it is possible to fire a single bi-directional nozzle in both directions simultaneously to generate a neutral force state for that nozzle which is useful in venting the system of excess gas pressure, and also to control the force obtained using one or more remaining nozzles for lateral propulsion without the necessity of varying the effective size of the nozzles. Thus, by firing adjacent nozzles together so that the result is a control force which passes through the center line of the vehicle, an increased number of force states in the pitch or yaw plane is made possible.